Edge electrodes with dielectric covers

ABSTRACT

The embodiments provide apparatus and methods for removal of etch byproducts, dielectric films and metal films near the substrate bevel edge, and chamber interior to avoid the accumulation of polymer byproduct and deposited films and to improve process yield. In an exemplary embodiment, a plasma processing chamber configured to clean a bevel edge of a substrate is provided. The plasma processing chamber includes a substrate support configured to receive the substrate. The plasma processing chamber also includes a bottom edge electrode surrounding the substrate support. The bottom edge electrode and the substrate support are electrically isolated from one another by a bottom dielectric ring. A surface of the bottom edge electrode facing the substrate is covered by a bottom thin dielectric layer. The plasma processing chamber further includes a top edge electrode surrounding a top insulator plate opposing the substrate support. The top edge electrode is electrically grounded. A surface of the top edge electrode facing the substrate is covered by a top thin dielectric layer. The top edge electrode and the bottom edge electrode oppose one another and are configured to generate a cleaning plasma to clean the bevel edge of the substrate.

CLAIM OF PRIORITY

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/440,561 filed on May 24, 2006, and titled “Apparatus andMethods to Remove Films on Bevel Edge and Backside of Wafer.” Thisapplication claims the priority of U.S. Provisional Application No.60/893,074, filed on Mar. 5, 2007, and titled “Edge Electrodes withDielectric Covers,” and U.S. Provisional application No. 60/893,069,filed on Mar. 5, 2007, and titled “Edge Electrodes with Variable Power.”These applications are incorporated herein by reference in theirentireties for all purposes.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to: (1) U.S. patent application Ser. No.______ (Attorney Docket No. LAM2P589), filed on the same date with thisapplication and entitled “EDGE ELECTRODES WITH VARIABLE POWER”, and (2)U.S. patent application Ser. No. 11/704,870, filed on Feb. 8, 2007 andentitled “METHODS OF AND APPARATUS FOR ALIGNING ELECTRODES IN A PROCESSCHAMBER To PROTECT AN EXCLUSION AREA WITHIN AN EDGE ENVIRON OF A WAFER”,both of which are incorporated herein by reference.

This application is also related to: (3) U.S. patent application Ser.No. 11/701,854, filed on Feb. 2, 2007 and entitled “APPARATUS FORDEFINING REGIONS OF PROCESS EXCLUSION AND PROCESS PERFORMANCE IN APROCESS CHAMBER”; and (4) U.S. patent application Ser. No. 11/697,695,filed on Apr. 6, 2007 and entitled “METHOD AND SYSTEM FOR DISTRIBUTINGGAS FOR A BEVEL EDGE ETCHER”, both of which are incorporated herein byreference.

BACKGROUND

The present invention relates in general to substrate manufacturingtechnologies and in particular to apparatus and methods for the removaletch byproducts from a bevel edge of a substrate.

In the processing of a substrate, e.g., a semiconductor substrate (orwafer) or a glass panel such as one used in flat panel displaymanufacturing, plasma is often employed. During substrate processing,the substrate (or wafer) is divided into a plurality of dies of squareor rectangular shapes. Each of the plurality of dies will become anintegrated circuit. The substrate is then processed in a series of stepsin which materials are selectively removed (or etched) and deposited.Control of the transistor gate critical dimension (CD) on the order of afew nanometers is a top priority, as each nanometer deviation from thetarget gate length may translate directly into the operational speedand/or operability of these devices.

Typically, a substrate is coated with a thin film of hardened emulsion(such as a photoresist mask) prior to etching. Areas of the hardenedemulsion are then selectively removed, causing parts of the underlyinglayer to become exposed. The substrate is then placed on a substratesupport structure in a plasma processing chamber. An appropriate set ofplasma gases is then introduced into the chamber and a plasma isgenerated to etch exposed areas of the substrate.

During an etch process, etch byproducts, for example polymers composedof Carbon (C), Oxygen (O), Nitrogen (N), Fluorine (F), etc., are oftenformed on the top and the bottom surfaces near a substrate edge (orbevel edge). Etch plasma density is normally lower near the edge of thesubstrate, which results in accumulation of polymer byproducts on thetop and on the bottom surfaces of the substrate bevel edge. Typically,there are no dies present near the edge of the substrate, for examplebetween about 5 mm to about 15 mm from the substrate edge. However, assuccessive byproduct polymer layers are deposited on the top and bottomsurfaces of the bevel edge as a result of several different etchprocesses, organic bonds that are normally strong and adhesive willeventually weaken during subsequent processing steps. The polymer layersformed near the top and bottom surfaces of a substrate edge would thenpeel or flake off, often onto another substrate during substratetransport. For example, substrates are commonly moved in sets betweenplasma processing systems via substantially clean containers, oftencalled cassettes. As a higher positioned substrate is repositioned inthe container, byproduct particles (or flakes) may fall on a lowersubstrate where dies are present, potentially affecting device yield.

Dielectric films, such as SiN and SiO₂, and metal films, such as Al andCu, can also be deposited on the bevel edge (including the top andbottom surfaces) and do not get removed during etching processes. Thesefilms can also accumulate and flake off during subsequent processingsteps, thereby impacting device yield. In addition, the interior of theprocess chamber, such as chamber walls, can also accumulate etchbyproduct polymers, which needs to be removed periodically to avoidbyproducts accumulation and chamber particle issues.

In view of the foregoing, there is a need for apparatus and methods thatprovide improved mechanisms of removal of etch byproducts, dielectricfilms and metal films near the substrate bevel edge, and chamberinterior to avoid accumulation of polymer byproducts and deposited filmsand to improve process yield.

SUMMARY

Broadly speaking, the disclosed embodiments fill the need by providingimproved mechanisms of removal of etch byproducts, dielectric films andmetal films near the substrate bevel edge, and chamber interior to avoidthe accumulation of polymer byproduct and deposited films and to improveprocess yield. It should be appreciated that the present invention canbe implemented in numerous ways, including as a process, an apparatus,or a system. Several inventive embodiments of the present invention aredescribed below.

In one embodiment, a plasma processing chamber configured to clean abevel edge of a substrate is provided. The plasma processing chamberincludes a substrate support configured to receive the substrate. Theplasma processing chamber also includes a bottom edge electrodesurrounding the substrate support. The bottom edge electrode and thesubstrate support are electrically isolated from one another by a bottomdielectric ring. A surface of the bottom edge electrode facing thesubstrate is covered by a bottom thin dielectric layer. The plasmaprocessing chamber further includes a top edge electrode surrounding atop insulator plate opposing the substrate support. The top edgeelectrode is electrically grounded. A surface of the top edge electrodefacing the substrate is covered by a top thin dielectric layer. The topedge electrode and the bottom edge electrode oppose one another and areconfigured to generate a cleaning plasma to clean the bevel edge of thesubstrate.

In another embodiment, a method of cleaning a bevel edge of a substratein a processing chamber is provided. The method includes placing asubstrate on a substrate support in the processing chamber, and flowinga cleaning gas into the processing chamber. The method also includesgenerating a cleaning plasma near the bevel edge of the substrate toclean the bevel edge by powering a bottom edge electrode with a RF powersource and by grounding a top edge electrode. The bottom edge electrodesurrounds the substrate support. The bottom edge electrode and thebottom electrode are electrically isolated from one another by a bottomdielectric ring. A surface of the bottom edge electrode facing thesubstrate is covered by a bottom thin dielectric layer. The top edgeelectrode surrounds an insulator plate, which opposes the substratesupport. A surface of the top edge electrode facing the substrate iscovered by a top thin dielectric layer.

In yet another embodiment, a method of cleaning a chamber interior of aprocessing chamber is provided. The method includes removing a substratefrom the processing chamber, and flowing a cleaning gas into theprocessing chamber. The method also includes generating a cleaningplasma in the processing chamber to clean the chamber interior bypowering a bottom edge electrode with a RF power source and by groundinga top edge electrode. The bottom edge electrode surrounds the substratesupport. The bottom edge electrode and the bottom electrode areelectrically isolated from one another by a bottom dielectric ring. Asurface of the bottom edge electrode facing the substrate is covered bya bottom thin dielectric layer. The top edge electrode surrounding aninsulator plate which opposes the substrate support. A surface of he topedge electrode facing the substrate is covered by a top thin dielectriclayer.

Other aspects and advantages of the invention will become apparent fromthe following detailed description, taken in conjunction with theaccompanying drawings, illustrating by way of example the principles ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be readily understood by the followingdetailed description in conjunction with the accompanying drawings, andlike reference numerals designate like structural elements.

FIG. 1A shows a schematic diagram of a substrate etching system with apair of top and bottom edge electrodes, in accordance with oneembodiment of the present invention.

FIG. 1B shows an enlarged region B of FIG. 1A, in accordance with oneembodiment of the present invention.

FIG. 1C shows an enlarged region A of FIG. 1A, in accordance with oneembodiment of the present invention.

FIG. 1C-1 shows an enlarged region A of FIG. 1A, in accordance withanother embodiment of the present invention.

FIG. 1D shows an enlarged region C of FIG. 1A, in accordance with oneembodiment of the present invention.

FIG. 1D-1 shows an enlarged region C of FIG. 1A, in accordance withanother embodiment of the present invention.

FIG. 1E shows the bevel edge cleaning plasma generated by RF poweredbottom electrode and grounded top edge electrode, in accordance with oneembodiment of the present invention.

FIG. 1F shows the bevel edge cleaning plasma generated by RF poweredbottom electrode and grounded top edge electrode, in accordance withanother embodiment of the present invention.

FIG. 2A shows a process flow of generating a bevel edge cleaning plasma,in accordance with one embodiment of the present invention.

FIG. 2B shows a process flow of generating a chamber interior cleaningplasma, in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Several exemplary embodiments for improved structures and mechanisms toremove etch byproducts, dielectric films and metal films near thesubstrate bevel edge, and chamber interior, to avoid polymer byproductand film accumulation and to improve process yield are provided. It willbe apparent to those skilled in the art that the present invention maybe practiced without some or all of the specific details set forthherein.

FIG. 1A shows a cleaning chamber 100 for cleaning substrate bevel edge,in accordance with one embodiment of the present invention. Cleaningchamber 100 has a substrate support 140 with a substrate 150 on top. Inone embodiment, the substrate support 140 is an electrode. Under suchcircumstance, the substrate support 140 can also be called a bottomelectrode. In another embodiment, the substrate support 140 is anelectrostatic chuck. Opposing the substrate support 140 is an insulatorplate 163. The insulator plate 163 can also be called a top insulatorplate 163. In one embodiment, there is a gas feed 161 coupled to thecenter of the insulator plate 163 to provide process gas. Alternatively,process gas can also be supplied to the edge of substrate 150 throughother configurations. The substrate support 140 is either made of aninsulating material or being coupled to a resistor 152 with highresistance value, if the substrate support 140 is made of a conductivematerial. In one embodiment, the resistance of the resistor is greaterthan 1 Mohm. The substrate support 140 is kept to having a highresistivity to prevent drawing RF power from the RF power source coupledto one of the edge electrodes. The substrate 150 has a bevel edge 117that includes a top and a bottom surface of the edge of the substrate,as shown in region B of FIG. 1A and enlarged region B in FIG. 1B. InFIG. 1B, bevel edge 117 is highlighted as a bold solid line and curve.

Surrounding the edge of substrate support 140, there is a bottom edgeelectrode 120, which can be made of conductive materials, such asaluminum (Al), anodized aluminum, silicon (Si), and silicon carbide(SiC). The surface of the bottom edge electrode 120 is covered by a thindielectric layer 126. In one embodiment, the thickness of the thindielectric layer 126 is between about 0.01 mm and about 1 mm. In anotherembodiment, the thickness is between about 0.05 mm and about 0.1 mm. Thethin dielectric layer 126 can be applied or formed in a number of ways,and one way can be through a deposition process. Alternatively, the thindielectric layer 126 can be formed separately form the bottom edgeelectrode 120 and be amounted on the bottom edge electrode 120.

To perform the deposition process, the bottom edge electrode 120 isplaced into a chamber where oxide growing chemicals are flown in topromote the formation of the thin dielectric layer 126. In oneembodiment, dielectric material of the thin dielectric layer 126 is atype of silicon dioxide. The thin dielectric layer 126 can also bedefined by other types of materials, including without limitationyttrium oxide (Y₂O₃), alumina (Al₂O₃), silicon carbide (SiC). In oneembodiment, the thin dielectric layer 126 is provided to reducecontamination in the process chamber. For example, if the bottomelectrode 120 is a made of aluminum (Al), aluminum would form compoundssuch as aluminum fluoride (AlF₃) with plasmarized radicals, such asfluorine radicals, in the cleaning plasma. The fluorine radicals wouldcorrode the electrode. When aluminum fluoride grows to a certain size,it would flake off the electrode and creates particles in the processingchamber. Therefore, it is desirable to have a cover for the bottomelectrode 120. The cover material should be stable (or inert) in thecleaning plasma. The thin dielectric cover 126 would reduce particleproblems for the processing chamber and increase device yield.

Between the substrate support 140 and the bottom edge electrode 120,there is a bottom dielectric ring 121 electrically separating thesubstrate support 140 and the bottom edge electrode 120. In oneembodiment, substrate 150 is not in contact with the bottom edgeelectrode 120. Beyond the bottom edge electrode 120, there is anotherbottom insulating ring 125, which extends the surface of the bottom edgeelectrode 120 facing substrate 150. The bottom dielectric ring 121 andthe bottom insulating ring 125 can be made of insulating materials, suchas a ceramic or alumina (Al₂O₃). The bottom edge electrode 120 iselectrically and physically coupled to a lower focus ring 124. In oneembodiment, the lower focus ring 124 is electrically coupled to the RFpower supply 123 for the substrate support 140. The lower focus ring 124is electrically and physically separated from the substrate support 140by an isolation ring 122. In one embodiment, the isolation ring 122 ismade of a dielectric material, such as ceramic or alumina. The bottomedge electrode 120 is RF powered through the lower focus ring 124 by anRF power source 123. The substrate support 140 is coupled to a movingmechanism 130 that enables the bottom electrode assembly to move up ordown. In this example, the bottom electrode assembly includes thesubstrate support 140, the bottom edge electrode 120, the bottomdielectric ring 121, the bottom insulating ring 125, and the isolationring 122.

Surrounding the insulator plate 163 is a top edge electrode 110,opposing the lower edge electrode 120. The top edge electrode 110 can bemade of conductive materials, such as aluminum (Al), anodized aluminum,silicon (Si), and silicon carbide (SiC). In one embodiment, between thetop edge electrode 110 and the insulator plate 163 is a top dielectricring 111. Beyond the top edge electrode 110, there is top insulatingring 115, which extends the surface of the top edge electrode 110 facingsubstrate 150. The top edge electrode 110 is electrically and physicallycoupled to a top electrode 160, which is grounded. In addition, thechamber walls 170 are grounded. The top electrode 160, the top edgeelectrode 110, the top dielectric ring 111, the top insulating ring 115,and the isolation ring 112, and the insulator plate 163 form a topelectrode assembly. In another embodiment, the top electrode 160 is RFpowered and the bottom edge electrode 120 is electrically grounded.

Based on the same reasons noted above for the thin dielectric layer 126,the surface of the top edge electrode 110 is also covered by a thindielectric layer 116. In one embodiment, the thickness of the thindielectric layer 116 is in about the same range as the thin dielectriclayer 126 noted above. The thin dielectric layer 116 is disposed overthe top edge electrode 110. The deposition and formation processes, andmaterials noted with respect to thin dielectric layer 126 also apply tothin dielectric layer 116.

FIG. 1C shows an encircled region A of FIG. 1A, which shows the top edgeelectrode 110 with the thin dielectric covering layer 116, in accordancewith one embodiment of the present invention. Alternatively, the surfaceof the thin dielectric covering layer 116′ is flush with the surface ofthe top dielectric ring 111 and the surface of the top insulating ring115, as shown in FIG. 1C-1. FIG. 1D shows an encircled region C of FIG.1A, which shows the bottom edge electrode 120 with the thin dielectriclayer covering layer 126, in accordance with one embodiment of thepresent invention. Alternatively, the surface of the thin bottomdielectric covering layer 126′ is flush with the surface of the bottomdielectric ring 121 and the surface of the bottom insulating ring 125,as shown in FIG. 1D-1. During bevel edge cleaning, the top edgeelectrode 110 is grounded through the top electrode 160. The bottom edgeelectrode 120 is powered by the RF source 123. In one embodiment, the RFpower is between about 2 MHz to about 60 MHz.

As described above, the thin dielectric layer 126 over bottom edgeelectrode 120 and the thin dielectric layer 116 over the top edgeelectrode 110 protect the bottom edge electrode 120 and the top edgeelectrode 110 from being corroded and reduce particle counts in theprocessing chamber. The thicknesses of the thin dielectric layers 126,116 should be kept low enough that the bottom edge electrode 120 and topedge electrode 110 can still function as electrodes. As described above,the thicknesses for thin dielectric layers 126 and 116 are between about0.01 mm and about 1 mm. In another embodiment, thicknesses for thindielectric layers 126 and 116 are between about 0.05 mm and about 0.1mm. The thin dielectric layer 126 can be applied or formed in a numberof ways, and one way can be through a deposition process. Other methodsinclude spraying the thin dielectric layer over the edge electrodes.Alternatively, the thin dielectric layer 126 can be formed separatelyform the bottom edge electrode 120 and be amounted on the bottom edgeelectrode 120, in accordance with one embodiment of the presentinvention.

The space between the substrate 150 and the insulating plate 160 is keptsmall, such as less than 1.0 mm, so that no plasma would generatebetween on the substrate surface that is beneath the insulating plate160. The top insulating ring 115 and bottom insulating ring 125 alsohelp confine the plasma generated be confined near the bevel edge.

The space between the substrate 150 and the insulating plate 163 is keptvery small, such as less than 1.0 mm, so that no plasma would generatebetween on the substrate surface that is beneath the insulating plate160. A plasma can be generated near the edge of the substrate 150 toclean the bevel edge, with the grounded bottom edge electrode 120 andthe grounded top edge electrode 110 providing returning electricalpaths, as shown in FIG. 1E.

A plasma can be generated near the edge of the substrate 150 to cleanthe bevel edge, with the grounded top edge electrode 110 providingreturning electrical paths, as shown in FIG. 1E, in accordance with oneembodiment of the present invention. Other arrangement of power supplyand grounding can also be used. For example, the top edge electrode 110is RF powered, by coupling a RF power supply to the top electrode 160,and the bottom edge electrode 120 is electrically grounded, by groundingthe lower focus ring 124, as shown in FIG. 1E in accordance with oneembodiment of the present invention. The key point is both the top edgeelectrode and the bottom edge electrode are each covered by a thindielectric layer to protect the surfaces of the edge electrodes.

During a substrate bevel edge cleaning process, the RF power source 123supplies RF power at a frequency between about 2 MHz to about 60 MHz anda power between about 100 watts to about 2000 watts to generate acleaning plasma. The cleaning plasma is configured to be confined by thetop dielectric ring 111, top edge electrode 110, the top insulating ring115, the bottom dielectric ring 121, the bottom edge electrode 120, andthe bottom insulating ring 125. The cleaning gas(es) is supplied throughthe gas feed 161 near the center of the insulator plate 163.Alternatively, the cleaning gas(es) can also be supplied through gasfeed(s) disposed in other parts of the process chamber 100.

To clean etch byproduct polymers, cleaning gases can include anoxygen-containing gas, such as O₂. Some amount, such as <10%, of afluorine-containing gas, such as CF₄, SF₆, or C₂F₆, can also be added toclean the polymer in one embodiment. It should be appreciated thatnitrogen-containing gas, such as N₂, can also be included in the gasmixture. The nitrogen-containing gas assists dissociation of theoxygen-containing gas. An inert gas, such as Ar or He, can also be addedto dilute the gas and/or to maintain the plasma. To clean a dielectricfilm(s), such as SiN or SiO₂, at the bevel edge 117, afluorine-containing gas, such as CF₄, SF₆, or a combination of bothgases, can be used. An inert gas, such as Ar or He, can also be used todilute the fluorine-containing gas and/or to maintain the cleaningplasma. To clean a metal film(s), such as Al or Cu, at the bevel edge117, a chlorine-containing gas, such as Cl₂, or BCl₃, or a combinationof both gases, can be used. An inert gas, such as Ar or He, can also beused to dilute the chlorine-containing gas and/or to maintain the plasmato clean the metal film(s).

In one embodiment, the space (or distance) between the top edgeelectrode 110 and the bottom edge electrode 120, D_(EE), is relativelysmall compared to the distance to nearest ground (D_(W)) of the bottomedge electrode 120 or top edge electrode 110. In one embodiment, thespace D_(EE) is between about 0.5 cm to about 2.5 cm. In one embodiment,the ratio of D_(W)/D_(EE) is greater than about 4:1, which ensuresplasma confinement. In one embodiment, D_(W) is the distance from thebottom edge electrode 120 to the near grounded chamber wall 170. Thechamber pressure is kept between about 100 mTorr to about 2 Torr duringthe bevel edge cleaning process. In one embodiment, the spacing betweenthe insulator plate 163 and substrate 150, D_(S), is less than about 1.0mm to ensure no plasma is formed between the top electrode 160 and thesubstrate 150 during the bevel edge cleaning process. In anotherembodiment, D_(S) is less than 0.4 mm.

The plasma generated in FIG. 1E is a capacitively coupled cleaningplasma. Alternatively, the bottom edge electrode 120 can be replacedwith an inductive coil buried in a dielectric material. The plasmagenerated to clean the bevel edge can be an inductively coupled plasma(generated by the bottom edge electrode 120). Inductive coupled plasmagenerally has a higher density than capacitively coupled plasma and canefficiently clean the bevel edge.

The plasma generated near the substrate edge and between the top edgeelectrode 110 and the bottom edge electrode 120 cleans the substratebevel edge of the substrate. The cleaning helps reduce the build-up ofpolymer at the substrate bevel edge, which reduces or eliminates thepossibility of particle defects impacting device yield. Making theentire bottom edge electrode and the top edge electrode with materialsinert to the cleaning plasma could be very costly. In contrast, using athin dielectric layer is a lot more cost effective. As described above,the thin dielectric layer can be mounted on the bottom edge electrodeand the top edge electrode. If a different cleaning chemistry is usedand the original thin dielectric layer is no longer inert to the newcleaning chemistry, the thin covers placed on the edge electrodes can beeasily replaced with covers made of materials that are inert to the newchemistry. This saves the money and time needed to remake the entirebottom edge electrode and the top edge electrode. In addition, after aperiod of usage, the surfaces of the bottom edge electrode and the topedge electrode can be cleaned or sanded. New layers (or coating) ofdielectric layers can be put on the edge electrodes. The edge electrodescan be kept unaffected with extended processing time.

FIG. 2A shows an embodiment of a process flow 200 for cleaning the beveledge of the substrate. The process starts at step 201 by placing asubstrate on a substrate support in a processing chamber. The process isfollowed by flowing a cleaning gas(es) through a gas feed into theprocessing chamber at step 202. At step 203, a cleaning plasma is thengenerated near the bevel edge of the substrate by powering a bottom edgeelectrode using a RF power source and by grounding a top edge electrode.The substrate support is either made of a dielectric material or beingcoupled to a resistor 152 with high resistance value to prevent drawingRF power from the bottom edge electrode to the substrate support. Adifferent process flow can be used, where the bottom edge electrode iselectrically grounded and the top edge electrode is powered by an RFpower source, in accordance with another embodiment of the presentinvention. A cleaning plasma to clean bevel edge can also be generatedin this configuration.

The configuration shown in FIG. 1A can also be used generate plasma toclean the chamber interior. During the chamber interior cleaning, thesubstrate 150 is removed from the process chamber 100. Therefore, theprocess can also be called waferless autoclean (WAC). In one embodiment,the pressure in the process chamber is kept below 500 mTorr. The lowerchamber pressure allows the cleaning plasma to diffuse through out thechamber interior. For waferless autoclean (or called chamber interiorclean), the distance requirement between the insulator plate 163 andsubstrate 150, D_(S), to be less than about 1.0 mm, is no longer needed.Similarly, the space requirement between the top edge electrode 110 andthe bottom edge electrode 120, D_(EE), of between about 0.5 cm to about2.5 cm is also not needed. Chamber interior leaning plasma does not needto be confined between the top edge electrode 110 and bottom edgeelectrode 120 or between the top insulating ring 115 and bottominsulating ring 125. The cleaning plasma needs to diffuse through outthe chamber interior to clean thoroughly.

As described above, to clean the bevel edge, the frequency of RF powerused is between about 2 MHz to about 60 MHz, or a mixture offrequencies. To clean the chamber interior, the frequency of RF power isbetween about 2 MHz to about 60 MHz, or a mixture of frequencies. Theplasma used to clean chamber interior normally has a higher plasmadensity than the plasma used to clean bevel edge; therefore, the RFpower used to clean chamber interior has higher frequency(ies) than theRF power used to clean bevel edge. In one embodiment, the RF source 123is a dual frequency power generator.

Different chemistries can be applied to perform WAC, depending on theresidues accumulated in the chamber interior. The accumulated residuecan be photoresist, dielectric materials, such as oxide and nitride, orconductive materials, such as tantalum, tantalum nitride, aluminum,silicon, or copper. The materials mentioned here are only examples. Theinventive concept can also be applied to other applicable dielectricmaterials or conductive materials.

FIG. 2B shows an embodiment of a process flow 250 for cleaning the beveledge of the substrate. The process starts at an optional step 251 byremoving a substrate from a processing chamber, assuming there is asubstrate in the processing chamber. If there is not substrate (orwafer) in the processing chamber, a chamber interior clean (or WAC) canstill be initiated. Under this circumstance, step 251 is not needed. Theprocess is followed by flowing a cleaning gas(es) through a gas feedinto the processing chamber at step 252. At step 253, a cleaning plasmais then generated inside the processing chamber by powering the bottomedge electrode using a RF power source, and grounding a top edgeelectrode. If the substrate support 140 is made of a conductivematerial, the substrate support 140 can be coupled to a resistor 152with high resistance value, such as greater than about 1 Mohm, toprevent drawing RF power to the substrate support 140. Alternatively,the substrate support 140 can be grounded.

A different process flow can be used, where the bottom edge electrode iselectrically grounded and the top edge electrode is powered by an RFpower source, in accordance with another embodiment of the presentinvention. A cleaning plasma to clean chamber interior can also begenerated in this configuration.

The improved apparatus and methods for cleaning of bevel edge, andchamber interior reduce undesirable build-up of etch by-products anddeposited films on the substrate or chamber interior and enhance thedevice yields. Due to the thin dielectric covers that are made ofmaterial(s) inert to the etching chemistry, corrosion of bottom edgeelectrode and to edge electrode is prevented or reduced. With the thindielectric layers covering the top edge electrode and bottom edgeelectrode, particle counts in the processing chamber are reduced.

Although the foregoing invention has been described in some detail forpurposes of clarity of understanding, it will be apparent that certainchanges and modifications may be practiced within the scope of theappended claims. Accordingly, the present embodiments are to beconsidered as illustrative and not restrictive, and the invention is notto be limited to the details given herein, but may be modified withinthe scope and equivalents of the appended claims.

1. A plasma processing chamber configured to clean a bevel edge of asubstrate, comprising: a substrate support configured to receive thesubstrate; a bottom edge electrode surrounding the substrate support,the bottom edge electrode and the substrate support being electricallyisolated from one another by a bottom dielectric ring, a surface of thebottom edge electrode facing the substrate being covered by a bottomthin dielectric layer; and a top edge electrode surrounding a topinsulator plate opposing the substrate support, the top edge electrodebeing electrically grounded, a surface of the top edge electrode facingthe substrate being covered by a top thin dielectric layer, the top edgeelectrode and the bottom edge electrode opposing one another and beingconfigured to generate a cleaning plasma to clean the bevel edge of thesubstrate.
 2. The plasma processing chamber of claim 1, wherein thethickness of the top thin dielectric layer and the bottom thindielectric layer both are between about 0.01 mm to about 1 mm.
 3. Theplasma processing chamber of claim 1, wherein the bottom edge electrodeis coupled to an RF power supply and the top edge electrode iselectrically grounded.
 4. The plasma processing chamber of claim 1,wherein the top edge electrode is coupled to an RF power supply and thebottom edge electrode is electrically grounded.
 5. The plasma processingchamber of claim 3, wherein a frequency of a RF power provided by the RFpower supply is between about 2 MHz and about 60 MHz.
 6. The plasmaprocessing chamber of claim 1, further comprising: a top insulating ringsurrounding and being coupled to the top edge electrode, wherein asurface of the top insulating ring that faces the substrate aligns withthe surface of the top edge electrode that faces the substrate; and abottom insulating ring surrounding and coupled to the bottom edgeelectrode, wherein a surface of the bottom insulating ring that facesthe top insulating ring aligns with the surface of the bottom edgeelectrode that opposes the top edge electrode, wherein the topinsulating ring and the bottom insulating ring confine the cleaningplasma generated by the top edge electrode and the bottom edgeelectrode.
 7. The plasma processing chamber of claim 1, wherein thebottom thin dielectric layer and the top thin dielectric layer are madeof a material inert to the cleaning plasma to prevent corrosion of thetop edge electrode and the bottom edge electrode and to reduce particlecounts in the processing chamber.
 8. The plasma processing chamber ofclaim 7, wherein the material is selected from the group consisting ofyttrium oxide (Y₂O₃), alumina (Al₂O₃), silicon carbide (SiC).
 9. Theplasma processing chamber of claim 1, wherein ratio of a distancebetween the bottom edge electrode or top edge electrode to a nearestground to a distance between the top edge electrode and the bottom edgeelectrode is greater than about 4:1.
 10. The plasma processing chamberof claim 1, wherein the substrate support is made of a conductivematerial and is coupled to a resistor with a resistance greater thanabout 1 Mohm.
 11. The plasma processing chamber of claim 1, wherein thedistance between the insulator plate and the a of the substrate facingthe insulator plate is less than about 1 mm.
 12. The plasma processingchamber of claim 1, wherein the distance between the top edge electrodeand the bottom edge electrode is between about 0.5 cm to about 2.5 cm.13. A method of cleaning a bevel edge of a substrate in an processingchamber, comprising: placing a substrate on a substrate support in theprocessing chamber; flowing a cleaning gas into the processing chamber;and generating a cleaning plasma near the bevel edge of the substrate toclean the bevel edge by powering a bottom edge electrode with a RF powersource and by grounding a top edge electrode, wherein the bottom edgeelectrode surrounds the substrate support, the bottom edge electrode andthe bottom electrode being electrically isolated from one another by abottom dielectric ring, a surface of the bottom edge electrode facingthe substrate being covered by a bottom thin dielectric layer, the topedge electrode surrounding an insulator plate which opposes thesubstrate support, a surface of the top edge electrode facing thesubstrate being covered by a top thin dielectric layer.
 14. The methodof claim 13, wherein the bottom thin dielectric layer and the top thindielectric layer are made of a material inert to the cleaning plasma toprevent corrosion of the top edge electrode and the bottom edgeelectrode and to reduce particle counts in the processing chamber. 15.The method of claim 14, wherein the material is selected from the groupconsisting of yttrium oxide (Y₂O₃), alumina (Al₂O₃), silicon carbide(SiC).
 16. The method of claim 13, wherein the substrate support isconfigured to having a high resistivity to prevent drawing RF power fromthe RF power source coupled to the bottom edge electrode.
 17. The methodof claim 13, wherein a distance between a surface of the substrate andthe insulator plate opposing the substrate support is less than 1 mm toprevent plasma being formed on a front surface away from the edge of thesubstrate.
 18. The method of claim 13, wherein the cleaning gascomprises either an oxygen-containing or a fluorine-containing gas. 19.The method of claim 13, further comprising: keeping a distance betweenthe top edge electrode and the bottom edge electrode is between about0.5 cm to about 2.5 cm.
 20. The method of claim 13, wherein ratio of adistance between the bottom edge electrode or top edge electrode to anearest ground to a distance between the top edge electrode and thebottom edge electrode is greater than about 4:1 to confine the cleaningplasma to be near the bevel edge.
 21. A method of cleaning a chamberinterior of an processing chamber, comprising: removing a substrate fromthe processing chamber; flowing a cleaning gas into the processingchamber; and generating a cleaning plasma in the processing chamber toclean the chamber interior by powering a bottom edge electrode with a RFpower source and by grounding a top edge electrode, wherein the bottomedge electrode surrounds the substrate support, the bottom edgeelectrode and the bottom electrode being electrically isolated from oneanother by a bottom dielectric ring, a surface of the bottom edgeelectrode facing the substrate being covered by a bottom thin dielectriclayer, the top edge electrode surrounding an insulator plate whichopposes the substrate support, a surface of the top edge electrodefacing the substrate being covered by a top thin dielectric layer. 22.The method of claim 21, wherein the bottom thin dielectric layer and thetop thin dielectric layer are made of a material inert to the cleaningplasma to prevent corrosion of the top edge electrode and the bottomedge electrode and to reduce particle counts in the processing chamber.23. The method of claim 22, wherein the material is selected from thegroup consisting of yttrium oxide (Y₂O₃), alumina (Al₂O₃), siliconcarbide (SiC).